Photochemistry of methoxy-substituted quinoline and isoquinoline N-oxides

Abstract

The photochemistry of quinoline 1-oxides and isoquinoline 2-oxides bearing a methoxy-group in the pyridine ring was investigated in protic and aprotic media. The formation of various photoisomers, viz. 3,1-benzoxazepines, 2(1H)-quinolones, N-(2-isocyanobenzyl)formamides, 4(1H)-quinolones, and 3-hydroxyquinolines from the different methoxyquinoline 1-oxides, and 1,3-benzoxazepines and 1(2H)-isoquinolones from the different methoxyisoquinoline 2-oxides, was observed along with deoxygenation and formation of products derived from hydration and decomposition of the primary products. The position of the methoxy-group has an important directing effect on the photoreactions.